Help the Oldies

Can someone from your wealth of experience and knowledgehelp us? Someone has bought us a cake mould in the shape of a Sunflower, it really looks great on the box, but unfortunately it didn't come with any recipes only instructions to 'pour the cake mix in the mould and bake'. The mixture has to be runny so as to avoid bubbles and fill all the mould. None of the cake reipes we have are runny they are all 'stodgy or thick' Any suggestions.
Sussexman
When it's brown it's done.
When it's black it's burnt